Shaft revolution counter



Nov. 4, 1958 o. l. HASZARD SHAFT REVOLUTION COUNTER Filed Dec. 3. 1956 L L I J H: bu L l- Lu 4 INVENTOR. OWEN l. HASZARD W ATTORNEYS United States Patent SHAFT REVOLUTION COUNTER Owen I. Haszard, Wenham, Mass., assignor to Amerac,

Incorporated, Weaham, Mass, a corporation of Massachusetts Application December 3, 1956, Serial No. 625,770

12 Claims. (Cl. 235-103) The present invention relates to counter dials and more particularly to dials wherein the readings may be accurately indicated for multi-turn devices that rotate through a substantial number of turns.

There are numerous types of apparatus, particularly such devices as otentiometers, microwave oscillators and equipment making use of a lead screw, wherein the position of a controlled element must be known with high accuracy for purposes of calibration and measurement. In such devices, not only must each complete rotation be counted, but fractions of a rotation must be accurately identified.

The present invention has as an object the provision of a counter dial of novel and compact construction, incorporating a smooth and efficient drive mechanism and also a counter by which the number of turns and fractions thereof may be accurately indicated.

Apparatus constructed in accordance with and embodying the several features of the invention is illustrated in the accompanying drawings in which,

Fig. 1 is a view in front elevation showing the counter dial face.

Fig. 2 is a view in side elevation, illustrating the device and its mode of attachment to a typical piece of equipment, illustrated as a portion of a microwave oscillator.

Fig. 3 is a view partly in section and on a substantially enlarged scale, taken on the line 3-3 of Fig. 1, the upper half of Fig. 3 being a vertical section and the lower half being a horizontal section as indicated in Fig. 1.

Fig. 4 is a sectional elevation taken on the line 44 of Fig. 3 but on a reduced scale, showing a portion of the drive train.

Fig. 5 is an oblique view of the mounting plate of the unit.

The counter dial is a compact cylindrical unit, the exterior of which is made up of front cover plate 10, rear mounting plate 12, and rotatble cylindrical sleeve 14. The sleeve 14 is knurled and forms the knob by which the dial mechanism and the apparatus on which the dial is mounted may be driven. Within the cylindrical knob are the base 16 and the housing 18 for the counter dials, the base and housing being secured by machine screws 20 (only a single screw appears in Fig. 3 by reason of the half-section). The front cover plate is preferably staked to the housing by drive pins 22. for a permanent connection.

The cylindrical knob 14 is provided on its interior adjacent one end with two gears, aninternal ring gear 24 having teeth around its inner periphery and a crown gear 26 having teeth along one axial edge. The assembly of the parts is such that the knob is journalled on the periphery of the base 16, while the ring gear 24 provides accurate axial guiding for the knob, the ring gear running with slight clearance between the front edge of the base plate 16 and the rear of the dial housing 18 when the base and housing are clamped together.

The ring gear 24 forms a part of the drive train between the knob and the output, while the crown gear 26 provides an independent drive to the counter mechanism within housing 18. The ring gear 24 meshes with spur gear 28 the hub of which is journalled in the base 16. A pair of recessed, socket-head set screws 30 permits secure locking of the gear to the shaft of the apparatus to be driven, a portion of such shaft being indicated at 32 for purposes of illustration. Access to the set screws is by radial passage 34 in the base 16, with a screw plug closure 36 for the corresponding passage in one knob, if desired. Rotation of the dial serves to bring first one and then the other set screw into alignment for tightening by a conventional wrench inserted through the passage.

By reason of the relative diameters of ring and spur gears 24 and 28, a ratio of the order of 1 /2 to 1 may be provided in the drive between knob and output. This is generally desirable in view of the number of turns frequently involved in devices having a lead screw for control purposes.

At the same time that the knob is driving the apparatus through ring gear 24 and spur gear 28, the counter is caused to record the number of rotations and fractions thereof on the dials visible through the cover plate 10. The counter dials 32 are contained within the housing 18 and are preferably of standard construction so as not to require detailed illustration. Each dial is numbered from Q to 9 so. that the four-digit counter permits readings up to 9999.

The counter shaft 34 is driven from the crown gear 26 by a gear train which comprises gear 36 on the counter shaft, and intermediate gear 38, 40 journalled on a stub shaft 42 secured in the housing 18. The guidance of the knob or sleeve 14, both axially and radially, is so precise that the gear 40 accurately meshes with the crown gear 26 as the knob is turned. The pitch diameters are preferably such that one hundred turns of the output shaft utilize the counter capacity. Thus a single turn represents one hundred units and the output shaft position may be therefore read to 1/100 of a turn for high accuracy.

In order to provide the maximum degree of compact ness consistent with ease of installation a special mounting plate construction is employed. The mounting plate 12 preferably of the same diameter as the knob 14, is provided with holes near its margin for securing to the panel of the apparatus. Fig. 2 shows the counter dial used in conjunction with a typical microwave oscillator 44 for rotating the lead screw 46 by which the tuning elements are adjusted. The mounting plate is shown secured to the panel 48 by screws 50.

After the mounting plate is secured to the panel, the counter dial may be placed in position on the plate. To retain the dial unit, a stud 52 projection from the mounting plate through a passage in the housing 18 and terminates in a recess in the front face of the device. A hollow headed screw 54 engages the end of the stud to provide a non'projecting retaining means, accessible from the front of the device. After the counter dial is mounted, the dial setting and the position of the instrument shaft may be brought into the desired relation or zero setting, after which the set screws are tightened to make the driving connection.

While the device has been illustrated and described as adapted for installation on the projecting shaft of equipment, it is obvious that the device itself may include a rearwardly projecting stub shaft, for which Fig. 3 is equally illustrative, for coupling to the apparatus rearwardly of the panel or in such other fashion as is convenient and appropriate.

The invention thus comprises a combined knob drive and indicating counter of compact and durable construction wherein the respective gear trains, though taking but little space, may nevertheless make use of gears of adequate dimensions to withstand long periods of use including operation at high speed, as when the setting is to be changed as rapidly as possible from one part of the range to another. A feature of the gear trains is that a standard four-digit counter may be utilized in a compact but relatively standard housing which is not required to provide bearing surfaces for the knob. A further feature is the arrangement by which the gear trains, other than those of the counter dials, are entirely outside and separate from the counter unit and its housing, with one train using limited axial space while the other train occupies a small space between the housing and the cylindrical knob.

The invention has been described in terms of a pre ferred embodiment, but it will be understood that the invention comprehends other forms and constructions embodying the principles of the invention within the scope of the appended claims.

I claim as my invention:

1. A counter dial unit for use with a multi-turn rotatable device, comprising a hollow rotatable knob, a fixed housing within the knob, counter mechanism within the housing and visible from the front thereof, a rotatable output member adapted to be connected to a rotatable device, driving connectionsbetween the knob and said output member comprising a ring gear carried by and extending around the inner periphery of the knob, and other driving connections between the knob and the counter mechanism.

2. A counter dial unit for use with a rnulti-turn rotatable device, comprising a hollow rotatable knob, a fixed housing within the knob, counter mechanism within the housing and visible from the front thereof, a rotatable output member adapted to be connected to a rotatable device, driving connections between the knob and said output member comprising a ring gear carried by and extending around the inner periphery of the knob, and other driving connections between the knob and the counter mechanism, said other connections including a crown gear carried by and extending around the inner periphery of the knob.

3. A counter dial unit for use with a multi-turn rotatable device, comprising a hollow rotatable knob, a fixed housing within the knob, counter mechanism within the housing and visible from the front thereof, a rotatable.

4. A counter dial unit for use with a multi-turn device comprising a rotatable hollow knob, a fixed housing within the knob, a base secured to the rear of the housing, counter mechanism within the housing and visible from the front thereof, a rotatable output member journalled in the base, an annular guideway intermediate the housing and base, driving connections between the knob and the output member comprising a ring gear carried by and extending around the inner periphery of the knob and received within the annular guideway between housing and base, the rotatable output member comprising a.

gear meshing with the ring gear, and other driving connections between knob and counter mechanism compris-.

ing a gear train outwardly of the housing and within the knob.

5. A counter dial unit for use with a multi-turn device comprising a rotatable hollow knob, a fixed housing within the knob, a base secured to the rear of the housing, counter mechanism within the housing and visible from the front thereof, a rotatable output member journalled in the base, an annular guideway intermediate the housing and base, driving connections between the knob and the output member comprising a ring gear carried by and extending around the inner periphery of the knob and received within the annular guideway between housing and base, the rotatable output member comprising a gear meshing with the ring gear, and other driving connections between knob and counter mechanism comprising a gear train outwardly of the housing and within the knob, said other connections including a crown gear carried by and extending around the inner periphery of the knob.

6. A counter dial unit for use with a multi-turn device comprising a rotatable hollow knob, a fixed housing within the knob, a base secured to the rear of the housing, counter mechanism within the housing and visible from the front thereof, a rotatable output member journalled in the base, an annular guideway intermediate the housing and base, driving connections between the knob and the output member comprising a ring gear carried by and extending around the inner periphery of the knob and received within the annular guideway between housing and base, the rotatable output member comprising a gear meshing with the ring gear, and other driving connections between knob and counter mechanism comprising a gear train outwardly of the housing and within the knob, said other connections including a crown gear carried by and extending around the inner periphery of the knob and a gear pivoted on the counter housing and meshing with the crown gear and coupled with the counter mechanism.

7. A counter dial unit for use with a multi-turn rotatable device, comprising a rotatable hollow knob, a fixed housing within the knob, a base secured to the rear of the housing, an aperture in the front of the housing, a multiple-dial counter mechanism within the housing and readable through the front aperture, a rotatable output member journalled in the base and comprising a gear, an annular guideway intermediate the housing and the base, a ring gear within the knob and meshing with the gear of the output member, said ring gear extending into the annular guideway to provide axial guidance for the rotatable knob, the knob having a portion overlying and journalled on the periphery of the base, a crown gear within the knob, and a gear train carried by the housing outwardly thereof and within the periphery of the knob and coupled to the counter mechanism. I

8. A counter dial unit for use with a multi-turn rotatable device, comprising a rotatable hollow knob, a fixed housing within the knob, a base secured to the rear of the housing, counter mechanism within the housing and visible from the front thereof, a rotatable output member journalled in the base, driving connections between the knob and the output member, other driving connections between the knob and the counter mechanism within the housing, and a mounting plate for said dial unit adapted to be secured to a panel of the rotatable device, said mounting plate having a peripheral configuration substantially that of the knob, and means extending through the housing from front to back and into demountable engagement with the mounting plate.

9. A counter dial unit for use with a multi-turn rotatable device, comprising a rotatable hollow knob, a

fixed housing within the knob, a base secured to the.

rear of the housing, counter mechanism within the housing and visible from the front thereof, a rotatable output member journalled in the base, driving connections between the knob and theoutput member, other driving connections between the knob and the counter mechanism within the housing, the rotatable output member having a hub and at least one radially disposed set screw therein, and a radial passage in base member and knob for access of a tool to actuate the set screw in the hub.

10. A counter dial unit for use with a multi-turn rotatable device, comprising a hollow rotatable knob, a fixed housing within the knob, counter mechanism within the housing and visible from the front thereof, a

fixed base for the housing, a rotatable output member extending through the base, said output member being rotatable about an axis eccentrically disposed relative to the axis of rotation of the knob, means carried by the periphery of the knob in driving engagement with the rotatable output member, driving connections between the knob and the counter mechanism, and fastening means extending between the base and the housing for fixedly securing the housing to the base.

11. A counter dial unit for use with a multi-turn rotatable device, comprising a hollow rotatable knob, a fixed housing within the knob, counter mechanism within the housing and visible from the front thereof, a fixed base for the housing, a rotatable output member journalled in the base, driving connections for actuating the rotatable output member from the knob comprising an internal ring gear carried by the knob, said driving connections occupying a portion of the area of the base and leaving another portion free of said connections, other driving connections between the knob and the counter mechanism, and fastening means extending between the base and the housing in the region free of driving connections for fixedly securing the housing to the base while permitting unrestricted rotation of the knob relative to the housing.

12. A counter dial unit for use with a multi-turn rotatable device, comprising a hollow rotatable knob, a fixed housing within the knob, counter mechanism within the housing and visible from the front thereof, a fixed base for the housing, output driving connections comprising a ring gear carried by the knob and a gear driven by the ring gear and journalled in the base, said gears occupying a portion of the area of the base and leaving another portion free of said output driving connections, other driving connections between knob and counter mechanism, and fastening means extending between the base and the housing in the region free of driving connections for fixedly securing the housing to the base while permitting unrestricted rotation of the knob relative to the housing.

References Cited in the file of this patent UNITED STATES PATENTS Matthew Ian. 15, 1957 

